I dont even have a clue?

Ok i have an aquaintence who used to be one of my best friends until he took me to a ditch and tried to rape me and i forgave him because he was a teen and probably didnt know his preferences yet. But then he kept asking me to do crazy things like paint his stomach down to his thighs, sleep in the same slepping bag in our underwear when we both have pajamas and sleeping bags of our own, daring me to prove i can have and orgasm when he was in the same room just " not looking" and once he even asked me to help him have and orgasm himself. And now me and him split ways but he still talks to me occaisionally and if i do ever go to hi house he hits me litterally with golf clubs. And now he is dating my best friend and i dont know what to do. The guy is huge and he tells me if i tell anyone he will do things to me but i need to tell my friend before its too late. But my friend isnt good at keeping secrets at all and i cabt tell my parents because they would just be mislead HELP!